1. Field of the Invention
The present invention is a pharmaceutical tablet formulation of (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinolin-2(1H)-one (Z)-2-butenedioate (1:1) and a method of using it to treat Parkinson's disease.
2. Description of the Related Art
U.S. Pat. No. 5,273,975 generically claims (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinolin-2(1H)-one (Z)-2-butenedioate (1:1), but does not disclosed it. It generically discloses that compounds are useful for treating Parkinson's disease.
U.S. Pat. No. 4,389,393 claims a sustained release pharmaceutical tablet formulation with less than 25.8% hydroxypropyl methylcellulose. Hydroxypropyl methylcellulose has been used extensively for producing sustained release (slow disintegration) tablet formulations.
U.S. Pat. No. 5,000,962 discloses a long acting tablet formulation which comprises more than 35 to 60% (by weight) of hydroxypropyl methylcellulose and lactose was used as an excipient. The present invention uses no lactose.
Dow's 1995 Formulating for Controlled Release With Methocel Premium Cellulose Ethers in FIG. 24 on page 21 discloses the use of starch with Methocel (hydroxypropyl methocellulose) for producing tablets containing theophylline. The tablets of the present invention do not contain theophylline but rather (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinolin-2(1H)-one (Z)-2-butenedioate (1:1). FIG. 20 on page 20 discloses a relationship between tablet size and the percent released with lactose. Normally starch is used in an amount up to about 15-20% for immediate release tablet formulations. However, in sustained release formulations it is not used because it is preceived to promote disintergation. Dow discloses the use of starch (excipient) at an amount of 52.6%. The tablet formulation of the present invention uses starch in an amount of more than 60%.
International Publication WO97/34932 discloses pharmaceutical tablets containing mechanically damaged starch which provide delayed, controlled and targeted release formulations. The present invention does not use mechanically damaged starch.
International Publication WO97/37639 discloses a controlled-release pharmaceutical tablet containing cross-linked amylose and hydroxypropylmethylcellulose and 10-30% of hydroxypropyl methylcellulose. The tablet formulation of the present invention uses no cross-linked amylose and has from 30-40% hydroxypropyl methylcellulose.